I. Definitions
As used herein, the phrase “group III-V” refers to a compound semiconductor including at least one group III element and at least one group V element. By way of example, a group III-V semiconductor may take the form of a III-Nitride semiconductor. “III-Nitride”, or “III-N”, refers to a compound semiconductor that includes nitrogen and at least one group III element such as aluminum (Al), gallium (Ga), indium (In), and boron (B), and including but not limited to any of its alloys, such as aluminum gallium nitride (AlxGa(1-x)N), indium gallium nitride (InyGa(1-y)N), aluminum indium gallium nitride (AlxInyGa(1-x-y)N), gallium arsenide phosphide nitride (GaAsaPbN(1-a-b)), aluminum indium gallium arsenide phosphide nitride (AlxInyGa(1-x-y)AsaPbN(1-a-b)), for example. III-Nitride also refers generally to any polarity including but not limited to Ga-polar, N-polar, semi-polar, or non-polar crystal orientations. A III-Nitride material may also include either the Wurtzitic, Zincblende, or mixed polytypes, and may include single-crystal, monocrystalline, polycrystalline, or amorphous structures. Gallium nitride or GaN, as used herein, refers to a III-Nitride compound semiconductor wherein the group III element or elements include some or a substantial amount of gallium, but may also include other group III elements in addition to gallium. A group III-V or a GaN transistor may also refer to a composite high voltage enhancement mode transistor that is formed by connecting the group III-V or the GaN transistor in cascode with a lower voltage group IV transistor.
In addition, as used herein, the phrase “group IV” refers to a semiconductor that includes at least one group IV element such as silicon (Si), germanium (Ge), and carbon (C), and may also include compound semiconductors such as silicon germanium (SiGe) and silicon carbide (SiC), for example. Group IV also refers to semiconductor materials which include more than one layer of group IV elements, or doping of group IV elements to produce strained group IV materials, and may also include group IV based composite substrates such as silicon on insulator (SOI), separation by implantation of oxygen (SIMOX) process substrates, and silicon on sapphire (SOS), for example.
It is noted that, as used herein, the terms “low voltage” or “LV” in reference to a transistor or switch corresponds describes a transistor or switch with a voltage range of up to approximately fifty volts (50V). It is further noted that use of the term “midvoltage” or “MV” refers to a voltage range from approximately fifty volts to approximately two hundred volts (approximately 50V-200V). Moreover, the term “high voltage” or “HV”, as used herein, refers to a voltage range from approximately two hundred volts to approximately twelve hundred volts (approximately 200V-1200V), or higher.
II. Background Art
Group III-V transistors, such as III-Nitride high electron mobility transistors (III-Nitride HEMTs), are often utilized in high power switching applications due to their performance advantages. For example, III-Nitride HEMTs combine a low on-state resistance with the ability to sustain relatively high operating voltages.
Despite their general robustness, however, group III-V power transistors can be susceptible to damage due to overcurrent conditions. For example, in operation, III-Nitride HEMTs may experience shoot through currents and/or may be exposed to short circuit load conditions, either of which can result in damage to or catastrophic failure of the III-Nitride HEMT.